Implantable electrode connector device

ABSTRACT

This proposal concerns a prosthesis, for a paraplegic with severed spinal cord, which operates by picking up motor signals from the still active nervous system and transmitting the same to stimulate spinal roots in the otherwise inactive part of the system, thereby bridging the lession. More particularly for this purpose, the invention proposes an implantable electrode connector device of flexible electrically insulating material having a base from which an array of leaves extend in a successive face-to-face array in the manner of a book, the leaves being resilient and tending to adopt a closed book configuration. In use of such a device, selected spinal roots are connected in the inter-leaf spaces with electrodes conveying appropriate motor signals.

United States Patent [1 1 Brindley 51 Feb. 27, 1973 IMPLANTABLE ELECTRODE CONNECTOR DEVICE [7 5] merits one Sliey ifi-in dley, "torment 1 England [73] Assignee: National Research Development Corporation, London, England 221 Filed: Abrii'ia'm'ii [21] Appl. No.: 133,692

[30] Foreign Application Priority Data April 17, 1970 Great Britain ..l8,482/70 [52] US. Cl. ..128/2.l E, 3/1, 128/418 [51] Int. Cl. ..A6lb 5/00, A6ln 1/02, A61f H00 [58] Field of Search ....l28/404, 418, 2.1 E, DIG. 26; 3/1;174/97,l38 R, 175

[56] References Cited UNITED STATES PATENTS I 3,157,181 11/1964 McCarty ..128/404 3,568,679 3/1971 Reif 3,405,715 10/1968 Hagfors .128/418 Primary ExaminerRichard A. Gaudet Assistant Examiner-Ronald L. Frinks Attorney-Cushman, Darby & Cushman ABSTRACT This proposal concerns a prosthesis, for a paraplegic with severed spinal cord, which operates by picking up motor signals from the still active nervous system and transmitting the same to stimulate spinal roots in the otherwise inactive part of the system, thereby bridging the lession. More particularly for this purpose, the invention proposes an implantable electrode connector device of flexible electrically insulating material having a base from which an array of leaves extend in a successive face-toface array in the manner of a book, the leaves being resilient and tending to adopt a closed book configuration. In use of such a device, selected spinal roots are connected in the inter-leaf spaces with electrodes conveying appropriate motor signals.

5 Claims, 1 Drawing Figure IMPLANTABLE ELECTRODE CONNECTOR DEVICE This invention concerns electrode connector devices and more particularly, but not exclusively, implantable devices for holding an array of electrodes in respective connections with spinal roots as part of a prosthesis for paraplegia. As more general background to the present invention it is useful to note that many instances of paraplegia involve severance of the spinal cord with consequent loss, amongst others, of lower limb control. However, in these instances, the spinal roots which emerge from the lower portion of the spinal cord are undamaged and, moreover, do not deteriorate signifi cantly with time. In this context it is suggested that some of the lost control be regained by way of a prosthesis which operates by picking up appropriate motivating signals from the still active part of the recipients nervous system and transmitting the same to stimulate the relevant spinal roots, thereby bridging the lesion.

For this purpose it is necessary to locate a number of stimulating electrodes (at least ten, and perhaps as many as a hundred) so that each will be in contact with, or close proximity to, a respectively different spinal root or one of a number of strands into which the relevant root may be artificially split. Clearly some form of device is needed for holding the electrodes and roots or root strands in this way and an object of the present invention is to provide such a device.

According to the invention there is provided an implantable, electrode connector, prosthetic device of flexible electrically insulating material comprising a base part and a plurality of generally leaf-like parts extending from said base part in successive face-to-face array in the manner of the pages of a book, said leaflike parts being resilient and tending to adopt a closed book configuration.

Since the device is made of flexible material it is more readily possible to insert the roots between the leaves without damage than would be the case with a relatively rigid device. Also, the overall flexibility of the device will allow movement thereof, after implantation, in sympathy with any movement of the surrounding body media without undue stress on the electrode/root connections.

The flexibility of the leaves with their tendency to close is advantageous in that a selected inter-leaf space can be opened for insertion of a root therein, whereafter the adjacent leaves are allowed to close and hold the root captive pending more permanent securement by suitable flexible adhesive to bond the leaves together.

The electrodes may be inserted in a similar manner to that above, but a preferred form of device has leaves extending from one surface portion thereof and is provided with respective bores leading from the opposite surface portion thereof into the inter-leaf areas for passage of individual electrodes therethrough.

Also, in a preferred form of device the base part is of elongate form with a plurality of leaf arrays extending transversely across the base at mutually spaced zones therealong, the leaves of each array being aligned longitudinally of the base.

A further preferred feature of the device is that the leaves have thickened peripheral portions remote from the base whereby adjacent leaves close to define a tunnel-like cavity for housing a root and an electrode terminal part.

In order to further clarify the present invention one embodiment of the currently preferred form thereof is diagrammatically illustrated by the accompanying drawing.

The illustrated embodiment has a generally stripform base part 1 having a plurality of leaf arrays 2 extending transversely across one major face of the base at mutually spaced zones along the base. Each array consists of a plurality of leaves 3 extending outwardly from the relevant face, the leaves being aligned parallel with the longitudinal axis of the base. The adjacent leaves of each array are mutually spaced apart except at their peripheries remote from the base where each leaf is thickened.

Individual passageways pass from the other major face of the base to respective inter-leaf spaces. Only one such passage is denoted at 4 in order to avoid lack of clarity by too much detail in the drawing.

The device is made of flexible material, suitably of a medical grade latex moulding material, such as Dow Corning 382 elastomer, for example, which has sufficient resilience for the purposes of the leaves as discussed above. The leaves can be bonded as discussed above with any appropriate adhesive which is compatible with the device material and is flexible. A silicone rubber glue, such as Dow Corning Silastic Medical Adhesive Type A, for example, is suitable for this purpose in connection with the above example for device material. The same, or a similar, adhesive is also to be used to secure the electrodes in position passing through the under face of the device. Both the moulding material and adhesive will, of course, be electrically insulating.

Bonding of the leaves is preferably effected only along the adjacent thickened peripheral parts. This avoids the possibility of any deleterious contact between the adhesive or a component thereof. For example, the above-mentioned more particular adhesive liberates acetic acid during setting, and this could cause damage to nerve fibers if allowed to contact a spinal root. With this constraint upon bonding, the root will not normally be immovably entrapped or effectively encapsulated, but be longitudinally movable through the inter-leaf tunnel. However, this is not disadvantageous. Access of cerebrospinal fluid to the contact region is harmless, and perhaps even beneficial, as is the case of in-growth of connective tissues.

While the present invention has been described more particularly in connection with stimulation of spinal roots in an artificial motor pathway, it can equally well find application in recording from spinal roots in an artificial sensory pathway. A further, but perhaps less likely application, may be found in stimulating or recording from peripheral nerves.

I claim:

1. An implantable, electrode connector, prosthetic device of flexible, electrically insulating material comprising: an elongate base part, and a plurality of arrays of generally leaf-like parts extending from said base part, each of said leaf-like parts being aligned in the longitudinal direction of said base part, the leaf-like parts of each array being disposed in a sequence extending traversely across said base part in successive face-to-face disposition in the manner of the pages of a book, said leaf-like parts being resilient and tending to adopt a closed book configuration for each array, and said arrays being disposed in mutually spaced sequence along said longitudinal direction.

2. A device according to claim 1 wherein said leaflike parts extend from one surface portion of said base part, and said base part is provided with respective bores leading from the opposite surface portion thereof into the spaces between adjacent ones of said leaf-like parts.

3. A device according to claim 1 wherein each of said leaf-like parts has a thickened peripheral portion remote from said base part to define with the remainder of the relevant part, an adjacent leaf-like part, and said base part, a tunnel-like cavity.

4. A device according to claim 1 wherein said base part is of strip form and each of said leaf-like parts is in the form of a substantially rectangular leaf extending from a common major surface of said base part.

5. A device according to claim 4 wherein each of said leaves has a thickened peripheral portion remotefrom said base part. 

1. An implantable, electrode connector, prosthetic device of flexible, electrically insulating material comprising: an elongate base part, and a plurality of arrays of generally leaflike parts extending from said base part, each of said leaf-like parts being aligned in the longitudinal direction of said base part, the leaf-like parts of each array being disposed in a sequence extending traversely across said base part in successive face-to-face disposition in the manner of the pages of a book, said leaf-like parts being resilient and tending to adopt a closed book configuration for each array, and said arrays being disposed in mutually spaced sequence along said longitudinal direction.
 2. A device according to claim 1 wherein said leaf-like parts extend from one surface portion of said base part, and said base part is provided with respective bores leading from the opposite surface portion thereof into the spaces between adjacent ones of said leaf-like parts.
 3. A device according to claim 1 wherein each of said leaf-like parts has a thickened peripheral portion remote from said base part to define with the remainder of the relevant part, an adjacent leaf-like part, and said base part, a tunnel-like cavity.
 4. A device according to claim 1 wherein said base part is of strip form and each of said leaf-like parts is in the form of a substantially rectangular leaf extending from a common major surface of said base part.
 5. A device according to claim 4 wherein each of said leaves has a thickened peripheral portion remote from said base part. 